1. Field
This disclosure relates generally to non-volatile memories (NVMs), and more specifically, to resistive random access memories (ReRAMs).
2. Related Art
The development of resistive random access memories is promising because many of the shortcomings related to floating gate non-volatile memories (NVMs) are overcome. ReRAM cells have a dielectric that can, using electrical means, be made to have conductive filaments that establish a low resistance. The process can be reversed whereby filaments are broken raising the resistance to a higher resistance. One of the issues though is the inconsistent formation of filaments near the sidewalls of the storage medium. When they do form, the low resistance is lower than when they don't form. Similarly, when they form, the higher resistance is also lower. Thus, the center point between the higher resistance and the low resistance is variable based on the degree to which filaments are formed on the sidewalls of the storage medium. This makes sensing more difficult. This same type of difficulty can arise due to vacancies, especially involving oxygen, that can transfer between the storage medium and the surrounding dielectric. The amount of the vacancies and the extent of movement can vary greatly, further increasing the variation in resistance for the low resistance and the high resistance. A further potential contributor to resistance variation is metal out diffusing from the metal oxide that is used as the storage medium. Outdiffusion can vary which will be another cause of resistance variation of the storage medium. Also, always a consideration is the ease with which any solution can be implemented. Since it is a different type of technology than normal semiconductor technology, the use of established techniques can be difficult in achieving a desired result for ReRAMs.
Accordingly there is a need for an ReRAM and a method of making the ReRAM that improves upon one or more of the issues described above.